| Standard label: | Other Comprehensive Income (Loss), Financial Liability, Fair Value Option, before Tax, after Reclassification Adjustment |
| Name: | us-gaap:OtherComprehensiveIncomeLossFinancialLiabilityFairValueOptionBeforeTaxAfterReclassificationAdjustment |
| Documentation: | Amount, before tax, after reclassification adjustment, of gain (loss) from increase (decrease) in instrument-specific credit risk of financial liability measured under fair value option. |
| Object type: | cm:Concept |
| Data type: | Monetary (xbrli:monetaryItemType) |
| Period type: | For Period (duration) |
| Balance type: | Credit |
| Abstract: | false |
| Workiva Wdesk Taxonomy Analyzer: | us-gaap:OtherComprehensiveIncomeLossFinancialLiabilityFairValueOptionBeforeTaxAfterReclassificationAdjustment |
| Label | Role | Language |
| Other Comprehensive Income (Loss), Financial Liability, Fair Value Option, before Tax, after Reclassification Adjustment | http://www.xbrl.org/2003/role/label | en-US |
| Other Comprehensive Income (Loss), Financial Liability, Fair Value Option, before Tax, after Reclassification Adjustment, Total | http://www.xbrl.org/2003/role/totalLabel | en-US |
| Reference | Role | Topic |
| FASB Accounting Standards Codification 220 10 45 10A (l) | http://www.xbrl.org/2003/role/disclosureRef | 220 |
| FASB Accounting Standards Codification 220 10 45 11 | http://www.xbrl.org/2003/role/disclosureRef | 220 |
| Part Of Roll Up: |
| us-gaap:OtherComprehensiveIncomeLossBeforeTax |